Direct vibrational energy transfer in zeolites

Abstract

Direct vibrational energy transfer in zeolitesBrugmans, M.J.P.; Bonn, M.; Bakker, H.J.; Lagendijk, A. Published in:Journal of Chemical Physics DOI:10.1063/1.470876 Link to publication Citation for published version (APA):Brugmans, M. J. P., Bonn, M., Bakker, H. J., & Lagendijk, A. (1996). Direct vibrational energy transfer in zeolites. Journal of Chemical Physics, 104, 64-84. DOI: 10.1063/1.470876 General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. With two-color picosecond infrared laser spectroscopy the dynamics of O-H and O-D stretch vibrations in zeolites are investigated. Zeolites appear to be good model systems to study transfer of vibrational energy in a solid. For the O-D vibrations, transient spectral holes are burnt in the inhomogeneously broadened absorption bands by saturating the absorption with a strong pump pulse. From the spectral hole widths the homogeneous absorption linewidths are obtained. The excited population lifetimes are determined using a time-resolved pump-probe technique, and in combination with the homogeneous linewidth the pure dephasing time is revealed as well. For high concentrations of O-H oscillators the vibrational stretch excitations are found to diffuse spectrally through the inhomogeneous absorption band. This spectral diffusion process is explained by direct site-to-site transfer of the excitations due to dipole-dipole coupling ͑Förster transfer͒. The dependences of the transient spectral signals on oscillator concentration and the results of one-color polarization resolved experiments confirm this explanation. The spectral transients are satisfactorily described by simulations in which the site-to-site transfer by dipole-dipole coupling is taken into account.

Dynamics of Infrared Photodissociation of Methanol Clusters in Zeolites and in Solution

“…For the time-resolved experiments intense picosecond (18 ps) tunable infrared (2200-4500 cm -1 ) pulses are generated by down-conversion of 1064 nm Nd:YAG pulses in LiNbO 3 crystals (for details, see ref 13). Our setup generates independently tunable, parallel polarized infrared pump (∼100 µJ) and probe (∼1 µJ) pulses, allowing for two-color experiments.…”

Bimodal dynamics of mechanically constrained hydrogen bonds revealed by vibrational photon echoes

“…The second explanation could be resonant (Förster) energy transfer of the NH-stretch excitation between NH groups. The rate of this energy transfer is given by 37,38 …”

Dynamical studies of zeolitic protons and interactions with adsorbates by picosecond infrared spectroscopy

“…The fact that a hole is burnt in the O-D... O~att absorption spectrum implies that this line is strongly inhomogeneously broadened [33]; there is a distribution of vibrational frequencies for the O-D groups, and the laser pulse can only excite those O-D groups resonant with the frequencies within the laser pump pulse at the center of the absorption band. This means there is an inhomogeneous distribution of catalytic sites in acid zeolites [11]. A possible cause for the inhomogeneous broadening is the inhomogeneous distribution of silicon and aluminum atoms throughout the lattice.…”

“…Knowledge of the interaction between BrOnsted hydroxyls and adsorbed species is therefore essential for a fundamental understanding of zeolite catalysis. Time-resolved infrared spectroscopy has proven to be a powerful tool in the investigation of the vibrational dynamics of the zeolite hydroxyl [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. This paper reports on a time-resolved infrared investigation of the effect of simple adsorbates on the dynamic properties of the catalytic BrOnsted hydroxyl.…”

“…The generated pair of laser pulses (pump and probe), independently tunable in wavelength from 2200 to 7200 cm l, are used for so-called pumpprobe experiments. In these experiments, the effect of a powerful pump ( ~ 150 /.L J) pulse are monitored by a weak probe pulse (~ 3 /z J), as a function of (i) time delay between pump and probe and (ii) frequency of the probe pulse: Transient spectra can be recorded as a function of delay time [11].…”